Safety spray gun trigger

ABSTRACT

Apparatus disclosed for disabling a paint spray gun triggering mechanism when the spray tip is removed, as for cleaning or replacement. The apparatus disables the spray gun trigger by shifting the trigger pivot point to an inactive position.

United States Patent Petrovic Oct. 21, 1975 SAFETY SPRAY GUN TRIGGER[56] References Cited [75] Inventor: John E. Petrovic, Coon Rapids,UNITED STATES PATENTS 3,410,491 11/1968 Malec 239/526 [73] Assignee:Graco Inc., Minneapolis, Minn 3,780,953 12/1973 Malec 239/526 [22]Filed: 1974 Primary ExaminerM. Henson Wood, Jr. 2 APPL 450 927 AssistantExaminer.lohn J. Love- Attorney, Agent, or Firm-Paul L. Sjoquist [44]Published under the Trial Voluntary Protest Program on January 28, 1975as document no. B 450,921 [57] ABSTRACT Apparatus disclosed fordisabling a paint spray gun [52] US. Cl. 239/526; 239/600; 251/89;triggering mechanism when the spray tip is removed, 251/1 1 1 as forcleaning or replacement. The apparatus disables [51] Int. Cl. B05B 11/00the spray gun trigger by shifting the trigger pivot point [58] Field ofSearch 239/526-528, to an inactive position.

12 Claims, 2 Drawing Figures US. Patent Oct. 21, 1975 3,913,844

SAFETY SPRAY GUN TRIGGER This invention relates to a spray gunapparatus, and more particularly to a safety trigger for insuring thathigh pressure fluid cannot be sprayed when the proper spray gun tip isnot attached.

The two basic techniques of paint spraying are air spraying and airlessspraying, both of which are accomplished using spray guns usually havingvery small spray orifices through which the paint mixture is ejected.According to the air spray technique, the paint is intermixed withpressurized air within the spray gun and the composite mixture issprayed through an orifice under pressure. In this case, the airpressure required is typically on the order of 10-50 pounds per squareinch. In airless spraying, the paint itself is maintained under highhydraulic pressures, typically SOD-3,000 pounds per square inch, andthis highly pressurized paint is forced through the spray orifice tocreate the necessary atomization. Because of the relatively small sizeof the orifice opening in both cases, it is frequently necessary toremove the orifice for cleaning and/or unplugging. When the orifice inan airless spray gun is removed there exists a potential hazard to theoperator because of the presence of paint in the spray gun under highhydraulic pressure. If the trigger on the spray gun should accidentallybe actuated, this high pressure paint could be ejected from the gun in ahigh velocity stream which, under certain circumstances, may havesufficient force to penetrate the body of a person. It has thereforebeen necessary to provide safety trigger features on airless spray gunsto lock the trigger against activation whenever the spray gun is notactually being used for spraying. A trigger-locking feature is describedin U.S. Pat. No. 3,633,828, issued Jan. 11, 1972 to the common assigneeof this invention, which trigger safety feature can be activated by theoperator to prevent accidental triggering of the spray gun.

The present invention provides yet another improvement in trigger safetydevices, and provides an improvement which may be used in conjunctionwith the feature described in the above-named patent. This inventiondisengages the trigger actuating mechanism whenever the spray tip,including the spray orifice, is removed from the gun. Because thetrigger disabling mechanism comes into play whenever the spray tip isremoved, it requires no other operator manipulation. As such, itprovides a completely safe trigger disabling mechanism which does notdepend upon operator actions such as are required with other triggersafety devices.

Briefly, the invention comprises a slidable rod positioned within thebody of the spray gun, and having its first end abutting the threadednut which holds the spray tip on the spray gun. The second end of theslidable rod abuts against the gun trigger pivot pin and serves to holdthe pivot pin in an operable position when the spray tip nut istightened. When the spray tip nut is loosened, such as for the purposeof removing the spray tip from the gun, the rod slides forward andrelieves the force on the trigger pivot pin, allowing the pin to movefreely within a constrained area. When the pin is freely movable it canprovide no pivot point from where a force can be leveraged to cause thetrigger to activate the spray gun valving mechanism. The triggereffectively hangs loosely in its mounting and becomes totally disengagedfrom triggering operation.

Accordingly, it is an object of this invention to provide a triggersafety apparatus for disabling a paint spray gun whenever the spray tipis removed.

It is a further object of this invention to disconnect the triggermechanism from operable linkage with the paint spray valve in an airlessspray gun whenever the airless spray tip is removed for cleaning ormaintenance.

It is another object of this invention to provide a trigger safetyshut-off mechanism which will automatically become activated upondisconnecting the gun spray tip, and without further operator activity.

These and other objects and advantages of this invention will becomeapparent with reference to the following description and claims, andfrom the drawings, in which:

FIG. 1 illustrates a spray gun having the inventive improvementincorporated therein; and

FIG. 2 illustrates the spray gun in a disabled configuration.

Referring to the drawings, FIG. 1 illustrates a spray gun having theinventive improvement incorporated therein. Portions of the spray gunare shown in crosssection to facilitate the understanding of the workingcomponents associated with this invention. Trigger 10 actuates thespraying mechanism of the spray gun by pulling it backward toward handle12. Trigger l pivots about a pin 15 which protrudes through the body ofthe spray gun and through holes near the upper end of trigger which aresized to accept pin 15. Pin has appropriate flanges or other lockingmeans at each of its ends to prevent it from falling out of the gun. Thepin 15 passage 18 through the gun body is constructed as an elongatedslot for purposes hereinafter to be described in conjunction with theoperation of the invention.

The spray gun is actuated by means of withdrawing valve rod 17 from itsseat near the front of the spray gun. Valve rod 17 is withdrawn whentrigger 10 is squeezed, there being a suitable connection betweentrigger 10 and the valve rod 17 retracting mechanism. For purposes ofexplanation, this is illustrated as contact point 19, it being assumedthat a suitable trigger edge bears against a shoulder on the valve rodretracting mechanism at contact point 19. The precise trigger retractingmechanism is not critical to this invention, it being required only thata trigger-valve rod mechanism contact point be established for actuatingthe valve rod mechanism. When valve rod 17 is retracted, paint or otherspray medium is admitted into the front passages of the spray gun and issprayed through spray tip 20. The paint spray is typically finelyatomized and, in the case of an airless spray gun, is forced through thesmall spray tip 20 orifice under a high hydraulic pressure. This highhydraulic pressure exists at all points rearward of spray tip 20 withinthe spray gun, and in particular exists within spray passage A spray tipretainer nut is threaded on to the spray gun and tightly clamps spraytip 20 against the gun. Retainer nut 25 also bears against the end ofslidable rod 23 and holds rod 23 in the position shown. The other end ofrod 23 bears against pin 15 to force pin 15 against the rearward edge ofslotted passage 18. Thus, the pivot point of trigger 10, as determinedby the position of pin 15 is located at the rearward portion of slottedpassage 18.

It frequently becomes necessary to remove spray tip 20 for cleaning.This can readily be accomplished by unscrewing retainer nut 25 from theend of the spray gun. However, when the spray tip 20 is removed, asillustrated in FIG. 2, the paint passage 21 becomes directly exposed.Thus, under these conditions, if trigger 10 is inadvertently squeezedhigh pressure paint will be ejected through paint passage 21 out of thespray gun without benefit of the atomizing characteristics of the spraytip. The result is that a high pressure stream of 10 paint is ejected,which stream may be injurious to and may penetrate objects against whichit is directed. Since this high pressure stream has sufficient force andhas been known to penetrate the skin ofa person, it becomes necessary toprovide safety features to avoid this probability. One safety featureknown in the prior art is trigger safety 27, which is a safety latch forpreventing trigger movement. When trigger safety 27 is rotated 90 fromthe position shown it bears against the rear surface of trigger l andprevents it from being squeezed toward handle 12. However, theeffectiveness of trigger safety 27 depends upon the operator rememberingto rotate it 90.

FIG. 2 illustrates the additional safety feature of the presentinvention. When tip retainer nut 25 is removed to enable replacement orcleaning of spray tip 20 it is no longer available to hold slidable rod23 against pin 15. Therefore, if trigger is squeezed under theseconditions, pin will slide forwardly in slotted passage 18 until itreaches the forward edge of slotted passage 18. In this position thepivot arm created between pin 15 and contact point 19 is insufficient toactuate the valve mechanism. Movement of pin 15 in slot 18 to the mostforward position also allows trigger 10 to contact safety 27, thuspreventing further movement of the trigger 10. Therefore, the valve 17cannot be retracted to allow the escape of high pressure paint throughpaint passage 21. Trigger 10 is effectively disabled and the spray gunbecomes inoperative until tip retainer nut is again replaced on thespray gun. The invention thereby provides a completely safe disablingmechanism for the spray gun.

Variations in the embodiment shown in the drawings may be made withinthe spirit of this invention. For example, rod 23 may be spring-loadedwithin the spray gun housing to force it away from contact with pin 15under all circumstances except when tip retainer nut 25 is securelyattached. Likewise, the end of rod 23 may be recessed within the spraygun housing to prevent the accumulation of paint thereon. Of course, rod23 may be provided with a suitable shoulder at any convenient point tohold it within the spray gun housing and to insure that it does not fallout when the spray gun is moved without the tip retainer nut 25 beingproperly positioned. All of these variations and others are contemplatedwithin the spirit of this invention, the inventive embodiment beingdirected essentially to an apparatus for controlling the spray guntrigger pivot in a manner to allow disabling of the trigger actuatingmechanism when the spray tip is removed.

I claim:

1. A spray gun trigger disabling apparatus effective on removal of thespray gun spray tip retainer, comprismg means for pivoting said triggerabout a pivot point for providing a spray gun trigger actuating leverageforce;

means for moving said pivot point to a position of disabling said spraygun trigger actuating leverage force;

a slidable rod connected between said means for moving the pivot pointand the spray tip retainer, whereby the removal of the spray tipretainer causes the pivot point to move to the disabling position.

2. Apparatus as claimed in claim 1 wherein the means for pivoting saidtrigger further comprises a pin extending between said trigger and saidspray gun.

3. Apparatus as claimed in claim 2 wherein said means for moving saidpivot point further comprises a slotted passage in said spray gun andwithin which said pin resides.

4. Apparatus as claimed in claim 3 wherein said slidable rod extendsbetween said slotted passage and the edge of said spray tip retainer.

5. Apparatus as claimed in claim 4, wherein the length of said slidablerod is selected to hold said pin in an actuating position when said tipretainer is secured on said spray gun.

6. A spray gun safety apparatus for disabling the spray gun trigger onremoval of the spray tip retainer from the spray gun housing,comprising:

a threaded portion on the spray gun for accepting and securing saidspray tip and spray tip retainer;

a pivot pin contacting said trigger with the spray gun housing;

a slotted passage in said spray gun housing for accepting said pivotpin; and

a slidable rod extending between said slotted passage and said spray tipretainer to hold said pivot pin in an actuating position when said tipretainer is se cured.

7. Apparatus as claimed in claim 6, further comprising a passage in saidgun housing of diameter slightly greater than said slidable rod, saidpassage extending between said slotted passage and a spray gun surfaceadjacent the edge of said secured tip retainer, wherein said slidablerod resides.

8. Apparatus as claimed in claim 7 wherein said pivot pin contacts thetrigger near the end of said trigger.

9. A spray gun trigger disabling apparatus effective on removal of thespray tip and retainer to prevent actuation of the spray gun fluidvalve, comprising:

a pivot pin passing through the spray gun body and through the trigger;

an oversized passage in said spray gun body for passage therethrough ofsaid pivot pin, whereby said pivot pin has freedom of movement thereinto at least two positions;

a movable member extending between said retainer and said pivot pin,whereby said member holds said pivot pin in a first position when saidretainer retains said spray tip and releases said pivot pin to a secondposition when said retainer is removed.

10. The apparatus of claim 9, further comprising a rotatable safetylatch means in said spray gun and extending into the path of movement ofsaid trigger, said latch means having a first position restrainingtrigger movement when said pivot pin is in its first position and havinga second position restraining trigger movement when said pivot pin is ina second position.

11. The apparatus of claim 10, wherein said movable member furthercomprises a rod slidable within a passage in said spray gun.

12. Apparatus as claimed in claim 11, wherein said oversized passage insaid spray gun body further comprises a slot elongated in the directionof said retainer.

1. A spray gun trigger disabling apparatus effective on removal of thespray gun spray tip retainer, comprising means for pivoting said triggerabout a pivot point for providing a spray gun trigger actuating leverageforce; means for moving said pivot point to a position of disabling saidspray gun trigger actuating leverage force; a slidable rod connectedbetween said means for moving the pivot point and the spray tipretainer, whereby the removal of the spray tip retainer causes the pivotpoint to move to the disabling position.
 2. Apparatus as claimed inclaim 1 wherein the means for pivoting said trigger further comprises apin extending between said trigger and said spray gun.
 3. Apparatus asclaimed in claim 2 wherein said means for moving said pivot pointfurther comprises a slotted passage in said spray gun and within saidpin resides.
 4. Apparatus as claimed in claim 3 wherein said slidablerod extends between said slotted passage and the edge of said spray tipretainer.
 5. Apparatus as claimed in claim 4, wherein the length of saidslidable rod is selected to hold said pin in an actuating position whensaid tip retainer is secured on said spray gun.
 6. A spray gun safetyapparatus for diabling the spray gun trigger on removal of the spray tipretainer from the spray gun housing. comprising: a threaded portion onthe spray gun for accepting and securing said spray tip and spray tipretainer; a pivot pin contacting said trigger with the spray gunhousing; a slotted passage in said spray gun housing for accepting saidpivot pin; and a slidable rod extending between said slotted passage andsaid spray tip retainer to hold said pivot pin in an actuating positionwhen said tip retainer is secured.
 7. Apparatus as claimed in claim 6,further comprising a passage in said gun housing of diameter slightlygreater than said slidable rod, said passage extending between saidslotted passage and a spray gun surface adjacent the edge of saidsecured tip retainer, wherein said slidable rod resides.
 8. Apparatus asclaimed in claim 7 wherein said pivot pin contacts the trigger near theend of said trigger.
 9. A spray gun trigger disabling apparatuseffective on removal of the spray tip and retainer to prevent actuationof the spray gun fluid valve, comprising: a pivot pin passing throughthe spray gun body and through the trigger; an oversized passage in saidspray gun body for passage therethrough of said pivot pin, whereby saidpivot pin has freedom of movement therein to at least two positions; amovable member extending between said retainer and said pivot pin,whereby said member holds said pivot pin in a first position when saidretainer retains said spray tip and releases said pivot pin to a secondposition when said retainer is removed.
 10. The apparatus of claim 9,further comprising a rotatable safety latch means in said spray gun andextending into the path of movement of said trigger, said latch meanshaving a first position restraining trigger movement when said pivot pinis in its first position and having a second position restrainingtrigger movement when said pivot pin is in a second position.
 11. Theapparatus of claim 10, wherein said movable member further comprises arod slidable within a passage in said spray gun.
 12. Apparatus asclaimed in claim 11, wherein said oversized passage in said spray gunbody further comprises a slot elongated in the direction of saidretainer.